Thrombin is among the most potent of the physiological agents to induce platelet aggregation which occurs during thrombosis and hemostasis. We have now identified a glycoprotein which is specifically cleaved by thrombin during thrombin-induced aggregation. In the coming year, we propose to isolate and characterize this receptor During the past year, we have obtained evidence indicating that platelet aggregation is mediated by a lectin on one platelet interacting with its receptor on an adjacent platelet. An immediate goal is to identify and isolate these proteins from platelets and determine their mechanism of action.